chloroaluminum-tetrasulfophthalocyanine and Retinal-Vein-Occlusion

Chloro-aluminum sulfonated phthalocyanine (CASPc) is a photoactive dye capable of generating photochemical reactions when excited with 675 nm light. We used CASPc to produce photochemical closure of retinal medullary ray vessels and choroidal vessels in normal rabbits. Irradiation prior to CASPc injection produced no photographic, angiographic, or histologic lesions in any eyes. Identical irradiation of medullary ray and choroidal vessels after CASPc injection produced complete vessel closure in all eyes. Histopathologic examination showed marked thrombosis of medullary ray and choroidal vessels, with minimal damage to contiguous tissues including the neurosensory retina. We conclude that CASPc can produce profound closure of normal retinal and choroidal vessels with minimal deleterious effect on surrounding tissues.

Topics: Aluminum; Animals; Choroid; Fluorescein Angiography; Fundus Oculi; Indoles; Lasers; Organometallic Compounds; Photochemotherapy; Rabbits; Radiation-Sensitizing Agents; Retinal Artery Occlusion; Retinal Vein Occlusion; Retinal Vessels; Thrombosis

Photodynamic therapy using chloroaluminum sulfonated phthalocyanine (CASPc) effectively closed experimental iris neovascularization induced in 6 eyes of cynomolgus monkeys by argon laser retinal vein occlusion. Neovascularization was followed by iris photography, fluorescein angiography, and histopathologic examination by light and electron microscopy. Intravenous injection of CASPc followed by irradiation with 675 nm light damaged endothelial cells and pericytes, leading to exposure of the basal lamina and thrombotic occlusion of the blood vessels. Surrounding tissue appeared preserved without evidence of thermal damage. Resorption of occluded vessels by macrophages began 2 to 3 days after photodynamic therapy. Neovascularization reappeared 7 days after photodynamic therapy, probably representing growth of new vessels. Photodynamic therapy with CASPc may be a useful adjunct in the treatment of iris neovascularization. The model is useful in elucidating the ultrastructural changes observed after photodynamic therapy using phthalocyanines.

Topics: Aluminum; Animals; Corneal Diseases; Disease Models, Animal; Endothelium, Corneal; Fluorescein Angiography; Indoles; Injections, Intravenous; Intraocular Pressure; Iris; Laser Therapy; Macaca fascicularis; Neovascularization, Pathologic; Organometallic Compounds; Photochemotherapy; Photography; Recurrence; Retinal Vein Occlusion